The present invention relates to a process for producing a distal end support member of an endoscopic treatment tool that is passed through a treatment tool insertion channel in an endoscope to be used for treatment in a body cavity.
FIG. 17 shows the distal end portion of endoscopic biopsy forceps which is one of the most commonly used endoscopic treatment tools. It comprises a flexible sheath 1, a manipulating wire 2 passed through the sheath 1 to be capable of moving back and forth along the longitudinal axis, a distal end support member 3 attached to the distal end of the sheath 1, and a pair of forceps cups 7 supported on the member 3 such that they can rotate about a support shaft 5 to open or close like beaks.
A groove 3a open toward the front end is formed in the front portion of the distal end support member 3. A drive mechanism 10 that is actuated by the manipulating wire 2 to drive the forceps cups 7 to open and close is held within the groove 3a which is in the form of a slit.
FIG. 18 shows the distal end support member 3 on its own. The rear portion 3A of the member 3 is formed like a tube into which the tip of the sheath 1 is to be inserted; as already mentioned, the groove 3a into which the drive mechanism 10 is to be held is formed in the front portion 3B of the member 3.
To fabricate the distal end support member 3, a rod-shaped workpiece must be subjected to at least two cutting operations, one being drilling from the back and the other being the formation of a groove in the front portion. In addition, the need to use a milling machine adds to the cost of parts fabrication.
An object, therefore, of the invention is to provide a process by which a distal end support member of an endoscopic treatment tool that has a drive mechanism holding groove portion and a sheath coupling portion can be fabricated at low cost.
According to the invention, a drive mechanism holding groove portion is formed by forging that portion of a cylindrical metal stock which is closer to its front end such that it is extruded along the longitudinal axis to form a slit of gap in the middle. A sheath coupling portion is formed by forging that portion of the metal stock which is closer to its rear end such that it is extruded in an annular shape in a direction opposite the first direction of extrusion. As a result, a distal end support member of an endoscopic treatment tool that has the drive mechanism holding groove portion and the sheath coupling portion can be fabricated at a very low cost.
As a preferred embodiment, the invention provides a process for producing a distal end support member of an endoscopic treatment tool which comprises a drive mechanism holding groove portion and a sheath coupling portion, the drive mechanism holding groove portion having a slit of gap formed to extend from its distal end so as to hold a distal end treatment member drive mechanism in a movable fashion and the sheath coupling portion being formed in an annular shape so that it can be coupled to the distal end of a sheath, characterized in that the drive mechanism holding groove portion is formed by forging that portion of a cylindrical metal stock which is closer to its front end such that it is extruded along the longitudinal axis to form a slit of gap in the middle whereas the sheath coupling portion is formed by forging that portion of the metal stock which is closer to its rear end such that it is extruded in an annular shape in a direction opposite the first direction of extrusion.
In order to extrude the sheath coupling portion by forging, the punch used to forge the drive mechanism holding groove portion may be replaced by a punch that defines an annular clearance from a die and which is used to perform forging in the same direction as the forging of the drive mechanism holding groove portion.
The punch and die that are used to forge the drive mechanism holding groove portion may have an annular clearance so that when the drive mechanism holding groove portion is extruded, the sheath coupling portion is simultaneously extruded between the punch and die.
A through-hole that crosses the slit of gap in the drive mechanism holding groove portion and which opens on both sides of the latter is pierced by extrusion by forging, provided that the side of the drive mechanism holding groove portion that first contacts a punch may be punched to make a hole and the resulting scrap is pushed forward until it contacts the other side of the drive mechanism holding groove portion and punches it to make another hole.
The present disclosure relates to the subject matter contained in Japanese patent application No. Hei. 11-327785 (filed on Nov. 18, 1999), which is expressly incorporated herein by reference in its entirety.